STYLE: Enforce using ITK macros when available

During careful review of this calss, some ivars were identified
that could be removed and made local variables of one function.

Identified where a pointer could be made const.

Prefer initialization to assignment for class constuctor.

Logic for printing message about too many interations was moved
to the parent class where the other termination messages are appended
to build up the message string.

Change-Id: I4767db52c0979c85bdf1a482d809e30aa6d1191c
Merge topic 'LBFGSBOptimizerDebug'

71e9fa1 STYLE: Enforce using ITK macros when available